This invention relates to photographic exposure control systems and, more particularly, to an automatic exposure control system employing a shutter latching arrangement.
A compact, single-lens reflex (SLR) camera having an electrically driven shutter-diaphragm system is described in the U.S. Pat. No. 3,820,128 issued to John P. Burgarella et al on June 25, 1974. The shutter-diaphragm system of that camera employs a pair of light-regulating blades mechanically biased to an open or viewing orientation and electromagnetically driven to a closed orientation such that the above system provides an open shutter orientation in the "off" condition of the camera. Modification of the above exposure system to render it suitable for non-SLR use by providing a normally closed shutter orientation is described and claimed in the commonly assigned, copending application Ser. No. 608,663, U.S. Pat. No. 3,995,295, of Lawrence M. Douglas filed herewith in which a shutter latch configured for holding the blades in a light-blocking orientation is released responsive to electrical control and actuation of the blade drive.
The latched blade arrangement of the above-noted copending application provides an economical, electrically controlled shutter system having a normally closed blade orientation while still preserving the electrically driven blade closing arrangement described in the above-referenced patent. However, since the return of the latch mechanism to its latch position is under the control of the camera operator, the latter can interfere with the automatic exposure sequence particularly where the automatic system includes timed events occuring prior to actual commencement of the exposure interval. For example, if minimum modification is desired for the system described in the above noted patent, the pre-exposure interval, normally employed for altering the system from viewing to exposure condition and which occurs between initial electrical actuation and shutter opening, must be accomodated. Hence, it is desirable to provide a shutter latch mechanism which is retained in a released condition until sufficient sequencing of the shutter system to ensure completion of the exposure cycle.
Consequently, an important object of this invention is to provide an improved automatic exposure control system.
Another object of this invention is to provide a shutter system having an improved latching arrangement.
Still another object of this invention is to provide an exposure control system having an economical, compact actuator and latch combination.
A further object of this invention is to provide a shutter latching arrangement which will not interfere with the exposure cycle.
A still further object of this invention is to provide an exposure control system having a latched shutter arrangement releaseable in accordance with electromechanical control.